The effect of the role of temperature and of fever on disease in man and experimental animals has been reviewed, using methods of library research. It appears that the localization, natural history, and susceptibility to disease is closely governed by temperature. This applies not only to infectious disease (bacterial, mycobacterial, fungal, protozoal, rickettsial, viral, helminthic), but also to metabolic and immunological diseases. This has suggested the need for a renewed look at the role of fever therapy or local hyperthermia in a variety of disease states.